1. Technical Field
The present invention relates to a device and method for manufacturing a microarray including beads having biological substances fixed on their surface, and a method for detecting a target substance.
2. Background
Recently, techniques of analyzing genes and protein have undergone rapid development and have advanced the identification of the mechanisms of cancers and other specific diseases. In order to facilitate disease diagnoses and medical checkups utilizing the analysis techniques, microarrays are expected to contribute. Examples of such microarrays include a DNA microarray and a protein microarray.
The DNA microarray is composed of a number of nucleic-acid probe spots with known base sequences aligned on the surface of a solid-phase base. Utilizing interactions (hybridization) of complementary nucleic acid sequences, the microarray captures a target nucleic acid and detects the nucleic acid by means of surface plasmon resonance (SPR) or fluorescent-molecule labeling. Since the base sequence of the nucleic-acid probe spot in which the nucleic acid has been detected is known, the DNA base sequence of a sample containing the gene of interest can be specified.
The protein microarray is used to capture target protein in biological samples (e.g. blood serum, urine, spinal fluid, synovial fluid, saliva, tissue homogenate) and various other samples containing protein (e.g. cell culture supernatant, cultured cell breaking fluid), utilizing its affinity for the surface of the spots.
For fixing the probes made of nucleic acid or protein, a method for fixing the probes as spots directly on a flat solid-phase base is described in Japanese Unexamined Patent Publication No. 2001-186880 (paragraphs 12 and 13), for example. Another method is for containing beads that, having multiple types of biological substances on their surface, in wells on a microtiter plate, fixing the beads on a terminal end of an optic fiber so as to identify them, and detecting reactions of the biological substances on the surface of the beads, which is exemplified in Japanese Unexamined Patent Publication No. 2002-533727 (paragraphs 9 and 12).
The latter method of fixing the probes made of nucleic acid or protein on the surface of the beads has advantages over the former method of fixing the probe spots directly on a flat base in various ways as follows: providing a broader surface of the solid base on which the probes are located and higher sensitivity, involving a lower risk of mutual contamination among adjacent spots, lowering the chance of the deactivation of the biological substances due to drying, and enabling proper processing of the surface of the solid-phase base that suits the types of the biological substances fixed on it. It is, however, difficult to correctly allocate a small amount of beads that have to be correctly selected from a single or adequately mixed multiple types of beads to reactive regions such as wells on a microtiter plate.
In order to address this issue, the present invention aims to provide a device and a method for manufacturing a bead array including beads having probes made of nucleic acid or protein fixed on their surface on a solid-phase base that makes it possible to accurately provide the beads in target reactive regions on the solid-phase base.